First of all take a pregnacy test since there is a chance you got pregnant days before the Depo shot (for the sake of the unborns health) Second of all It could just be nothing much but the side effects of the Depo shot. Some girls regret getting that shot since they began to spot and get cramps..and it misses up their period cycle. But eventually it goes back to normal deppending since everyone is different. The pull out method works but evetually there's a chance of pre-*** which you can still get pregnant. All birth control have side effects which is why it's best to look up first before getting taking it. Good Luck.
Pregnancy is always a possibility but I wouldn't say that you are just based on those two things. When is your period due?